The Research Triangle Institute (RTI) engages in a broad spectrum of research activity involving the use of live vertebrate animals. Current research programs include the studies of toxicology, teratology, metabolism, pharmacokinetics of xenobiotic materials, reproduction and fertility, (including assessment of chemical effects on fertility and development of effective contraceptive drugs), immunology, methods for better delivery of drugs, including the use of biodegradable polymer implants, and assessment of the mutagenic effects of chemicals and x-rays in mice. These programs are being conducted in an animal research facility that was renovated in 1987-1088 in order to bring it into compliance with the more stringent standards associated with conducting toxicological and carcinogenic research. RTI is accredited by AAALAC and must meet their requirements as well as those of the USDA. In addition RTI is bound by the requirements listed in the PHS "Guide for the Care and Use of Laboratory Animals". Moreover, RTI conducts most animal studies under FDA and EPA Good Laboratory Practice regulations, which are very stringent regarding control, monitoring and documentation of the environment of animals on study. The current animal research facility was expanded in 1987-1988 to incorporate a complete clean-return corridor system and to add 10 more rooms for animal studies at a total cost of $2.58 million dollars, of which $0.47 million was provided by a grant from NIH. Due to budgetary constraints, the complete HVAC system could not be upgraded at that time. The current proposal requests support to upgrade and expand the present HVAC system to support conditions (temperature and particularly humidity) required for rabbits (for which there is an increasing demand), to provide redundancy to prevent loss of valuable experiments, and to upgrade the control and monitoring system to meet current stringent requirements for maintenance and recording of environmental conditions.